Danin et al. (Israel J. Bot. 27: 177–211. 1978) recognized a series of eight subspecies, but they are rather poorly correlated with geography and their status needs re-evaluation. The Chinese material seems to belong to the most common and weedy form placed in subsp. oleracea. There has been some selection of more robust forms for use as a vegetable; these are sometimes placed in subsp. sativa (Haworth) Celakovský.

The plants, which are common weeds of cultivation, are eaten as a vegetable and used for medicinal purposes.